牙鲆仔鱼在混合饵料期的摄食能力及饵料选择性

研究了牙鲆仔鱼在轮虫、卤虫无节幼体混合饵料期的摄食能力及饵料选择性指标,结果表明,在开口后的第8天、第10天、第11天以轮虫为喜好性饵料,且最适的密度为10ind/mL,在开口后第10天对卤虫无节幼体开始有了一定的摄食能力;在开口后的第13天以后以卤虫无节幼体作为喜好性饵料;在开口后第15天开始放弃对轮虫的选择,可以以卤虫无节幼体作为唯一的食物来源;在轮虫、卤虫无节幼体混合饵料期,轮虫的最适密度是7～10ind/mL,卤虫无节幼体的最适密度是5～7ind/mL。     

轮虫培育池浮游生物的时空分布

在1995－1996年期间，对黑龙江、内蒙、辽宁3个地区11个池塘浮游生物的时空分布进行了研究。结果表明，浮游植物在池的上、下风位水平分布和表、底层垂直分布存在显著差异。轮虫的水平分布与风浪及水体溶氧状况有关，无风（或微风）时，上、下风位无明显差异。有风浪时，上风位比下风位高出1倍多。水体缺氧时，下风位比上风位高出4倍多，轮虫的垂直分布在溶氧充足时，上、下风位表层均低于底层；而在水体缺氧时，上、风位表层高出底层近3倍。桡足类的水平分布上风位比下风位高出2－4倍，垂直分布无明显差异。文中还讨论了轮虫池浮游生物分布的某些规律和成因及其在生产实践中的意义。     

轮虫石蜡切片制作方法的改进

轮虫个体微小、组织柔软,对外界环境刺激反应较强烈,同时体表覆盖有角质层,采用常规的石蜡切片技术,难以切出完整的切片。通过对传统制片技术的改进,可以使标本接近自然状态,取得了比较理想的效果。     

Use of flubendazole as a therapeutic agent against rotifers (Brachionus plicatilis) in intensive cultures of the harpacticoid copepod Tisbe holothuriae

Copepods are well known to be the optimal live feed for most species of marine fish larvae. Still copepods are rarely used in marine hatcheries worldwide. Lack of efficient production techniques are among the reasons for this. Consequently, Artemia and rotifers are utilized in commercial settings. One problem in intensive production of copepods is contamination with rotifers. Rotifers have higher growth rates than copepods and consequently will compete out the copepods when accidentally introduced to the copepod production systems. Once contamination has occurred, the only cure has been to shut down production and subsequently use a therapeutic agent to eliminate all zooplankton in the system before restart with a stock culture free of rotifers. We tested flubendazole as a mean of controlling rotifers (Brachionus plicatilis) in intensive laboratory cultures of the harpacticoid copepod (Tisbe holothuria). Flubendazole was lethal to rotifers in concentrations as low as 0.05 mg L^?1. There was no significant effect on the concentration of copepods, even at the highest concentration tested, i.e. 5.0 mg L^?1 flubendazole. We conclude that flubendazole is an effective drug for control of B. plicatilis in T. holothuriae batch cultures.     

Enhancing rotifer Brachionus calyciflorus population growth with commercial probiotics

The effect of a commercial probiotic (NanoCrusta, Altacrusta, Mexico City, Mexico) on the growth performance of Brachionus calyciflorus Pallas, 1766, was evaluated. In a first approach, probiotics were supplied in four densities (2.0 × 10³, 1.1 × 10⁵, 2.1 × 10⁵ and 2.1 × 10⁶ cells/ml), alone and in combination with Chlorella vulgaris (1 × 10⁶ cells/ml). The test rotifer did not grow on the probiotic alone. However, when probiotics + C. vulgaris were added, the maximum densities (D_max; ind/ml) and population growth rates (r) observed were higher. In the second experiment, probiotics were supplied at five higher densities (2.1 × 10⁶, 4.2 × 10⁶, 8.5 × 10⁶, 1.7 × 10⁷ and 3.4 × 10⁷ cells/ml) with C. vulgaris and a control treatment with only C. vulgaris (probiotic‐free). Treatments supplied with probiotics between 2.1 × 10⁶ and 1.7 × 10⁷ cells/ml showed significantly higher D_max and r than the control treatment. The results showed a positive effect of probiotic bacteria when supplied with C. vulgaris. The best outcome showed a D_max 2.16 times and an r 1.63 times higher than the density of the control treatment. Growth rates were higher in the treatments with probiotics compared to the control. We conclude that application of NanoCrusta is feasible to improve B. calyciflorus production, but the effects need to be tested in larger scales.     

Fish‐processing wastes as an alternative diet for culturing the minute rotifer Proales similis de Beauchamp

We evaluated the suitability of fish waste diet (FWD) for culturing the minute rotifer Proales similis through the observation of their population growth and particle size selective feeding. A total of five treatments either with Nannochloropsis oculata or FWD (0.75 and 0.50 g/L) or the combination of N. oculata and FWD were set up in triplicates. P. similis were cultured in diluted natural seawater (8 g/L salinity) and 26 ± 1°C with the diet treatments being applied randomly. We daily monitored the rotifer density, the number of bacteria and the water quality in all the cultures. The population density of P. similis increased exponentially in all treatments, while the mean growth in FWD 0.75 g/L was significantly higher (p < .05) than that in the control. Addition of N. oculata to FWD resulted to lowered P. similis population growth. Bacterial colony count was high in FWD and introduction of P. similis to the diet decreased their density. The estimated bacteria ingestion rates were generally in the range of 6.03 × 10²–1.24 × 10⁴ bacteria/rotifer/hr and there was a positive linear relationship between bacterivory and rotifer population growth. We also observed a shift in the particle size distribution with a reduction in the frequency and concentration of small‐sized particles (<2.5 μm) at day 6. These results accentuate the potential of fish‐processing waste as diet for culturing P. similis which feeds on bacteria and small particles (≤2.5 μm) that are by‐products of degradation of this diet.     

Effects of docosahexaenoic acid on growth,survival and swim bladder inflation of larval amberjack ( Seriola dumerili, Risso)

The effect of docosahexaenoic acid (DHA) on the growth performance, survival and swim bladder inflation of larval Seriola dumerili during the rotifer feeding period was investigated in two feeding experiments. Amberjack larvae at 3 day post hatching were fed rotifers enriched with (1) freshwater C hlorella (Chlo), (2) a mixture (2:1, v/v) of Chlo and DHA‐enriched C hlorella (DHA‐Chlo), (3) DHA‐Chlo and (4) DHA‐Chlo and commercial DHA emulsion, in triplicate for 7 days. The average DHA contents of the rotifers were 0.0, 0.4, 1.0 and 1.9 mg g^?1 DM respectively. The survival rate was improved by the enrichment of rotifers with DHA‐Chlo alone, and DHA‐Chlo and emulsion. Growth and swim bladder inflation of fish fed rotifers enriched with DHA‐Chlo were significantly (P < 0.05) improved, however, with increased levels of DHA further improvement was not found. DHA content in the larval whole body proportionally increased with the DHA level in the rotifers. These results suggest that DHA enrichment of rotifers is effective to improve the growth, survival rate and swim bladder inflation of amberjack larvae. The DHA requirement of amberjack larvae is estimated to be 1.5 mg g^?1 on a dry matter basis of rotifers.     

不同溶剂及配比对轮虫脂肪提取的影响

研究了提取溶剂、次数以及溶剂的配比对轮虫脂肪提取的影响。分别用氯仿甲醇体积比为2:1、1:1、1:2,苯石油醚体积比2:1、1:1、1:2,丙酮石油醚1:4、3:7、2:3作为提取溶剂,提取冻干轮虫(Brachionus rotundiformis)样品脂肪,测定脂肪含量与皂化值,筛选得出3种提取溶剂的最佳配比;比较提取次数为1～3次间脂肪含量的差异,得出最佳提取次数;将3种最佳配比与索氏提取法(国标)提取样品脂肪进行比较,测定脂肪含量与皂化值。结果显示,在冻干轮虫脂肪提取中,提取次数对样品脂肪含量没产生显著影响(P>0.05);3种溶剂的最佳配比分别为氯仿甲醇2:1、苯石油醚1:2、丙酮石油醚2:3;其中丙酮石油醚2:3处理组的脂肪含量和皂化值分别达到9.71%和198,均显著高于索氏提取法(国标)和其余处理组(P<0.05)。故轮虫脂肪提取1次为宜,最佳溶剂及配比为丙酮石油醚体积比2:3,本方法具有提取高、时间短、安全性高、成本低等优点,具有一定的实际应用价值。     

三峡水库小江回水区原生动物和轮虫群落结构特征及其与环境因子关系初步研究

2008年春、夏、秋和水华发生末期,对三峡水库小江回水区的原生动物、轮虫群落进行了调查,共监测到原生动物52种、轮虫35种;其中,原生动物秋季种类最多,有30种,轮虫夏季种类较多,有25种。水华发生末期的现存量最高,但多样性指数最低。理化参数的多因素方差分析、聚类分析结果表明,小江回水区水环境具有明显的时间异质性。从物种组成聚类结果来看,不同时间的原生动物和轮虫群落组成不同,且与水环境的时间异质性并不一致。浮游动物现存量与环境因子关系的冗余分析(RDA)结果显示,水温与浮游动物群落现存量呈显著正相关。